Normal-incidence, high-frequency bottom penetration in the soft gassy sediments of Eckernforde Bucht, Germany

In June and July of 1994, a series of high-frequency bottom penetration measurements were made in the gassy sediment of Eckernforde Bucht, Germany. A multielement hydrophone array was buried in the sediments and insonified by a normal-incidence signal. Measurements were made of the water–sediment insertion loss and signal level as a function of frequency (15–40 kHz) and hydrophone depths (0, 14, 28, 71, 122, 152, and 158 cm). Results showed that hydrophones located in a gassy sublayer had signal levels that were higher than the signal level at a hydrophone located just below the sediment–water interface.